Polyetherketone is noticed as an engineering plastic superior in heat resistance, strength, stiffness, flame retardance, chemical resistance, etc., particularly in respect to its uses for electrical parts, automobile parts, and the like.
In these application fields, there is a further need for this sort of material having higher heat resistance, strength, and stiffness while retaining the good flame retardance, chemical resistance, hot water resistance, processability, etc. which are characteristic of polyetherketone.
It is known that polyetherketone is fairly improved in strength, stiffness, heat resistance, and other properties by incorporating thereinto a fibrous reinforcing material such as glass fiber, carbon fiber or the like. However, compositions loaded with fibrous reinforcing material have drawbacks such that they exhibit high anisotropy, coarse surfaces, and inferior appearance and abrade processing machines and molds. By incorporating a powdery or flaky filler such as a calcium carbonate, mica, or glass bead filler into polyetherketone, this polymer can be improved in dimensional stability but insufficiently in stiffness. In addition, such filler incorporation lowers the impact strength, making the polymer brittle.
To overcome these drawbacks, there have been proposed resin compositions comprising polyetherketone and potassium titanate fibers.
However, these compositions have a drawback in that the melt viscosity and molding instability in melt molding (e.g. injection molding) increase on account of the stagnation of melt at elevated temperatures as the load of potassium titanate fibers is increased to achieve greater reinforcing effect.